Hydrofluorocarbons, HFC's, are of great interest due to their potential to replace ozone-depleting chlorofluorocarbons, CFC's, which are used in a variety of applications, including refrigerants, solvents, foam blowing agents, and aerosol propellants. For example, 1,1,2,2,3-pentafluoropropane, HFC-245ca, has been identified as a potential refrigerant and foam blowing agent in Japanese patent publication No. 02265933.
The art is actively searching for methods to reduce CFC's to HFC's in order to find suitable replacements for ozone-depleting CFC's. For example, WO 90/08753 to Morikawa et al. disclose a reduction process by which hydrogen-containing 2,2-difluoropropanes are produced. In the disclosed process, the reduction is performed using either zinc and a hydrogen forming agent or hydrogen in the presence of a supported metal catalyst. Morikawa et al. broadly disclose a great number of starting materials, one of which is 1,3-dichloro-1,1,2,2,3-pentafluoropropane, which may be used to form any number of HFC's, one of which is 1,1,2,2,3-pentafluoropropane. Morikawa et al. further disclose the equivalency, for purposes of reducing CFC's, of a wide variety of catalysts supported on a number of inert materials, including both alumina and carbon. Among the many catalysts listed are platinum group elements. Morikawa et al., however, provide no recognition of the superiority of certain supported catalysts in CFC reduction reactions.
As another example of catalytic reduction, Japanese publication No. 3284638 discloses the catalytic hydrogenation of haloethanes of the formula CF.sub.2 xCyCl.sub.2, where x and y may be fluorine or chlorine. The hydrogenation is carried out in the presence of a palladium-iron-silver catalyst to produce HCFC's of the formula CF.sub.2 xCHyCl.
The present invention provides a method for catalytically reducing HCFC-225cb to EFC-245ca using a supported platinum group metal catalyst. It has been unexpectedly discovered that the process of the present invention provides both an economical method for the production of BFC-245ca and a method that is amenable to large scale manufacture.